1. Field of the Invention
The present invention relates to a cleaning apparatus and a cleaning method for a magnetic filter for removing metal powder from a treatment liquid in a container in a pre-painting process for, for example, the body of an automobile.
2. Description of Related Art
Conventionally, as equipment for removing metal powder contained in treatment liquid, which is used, for example, when treating the body of an automobile with a pre-painting process, a metal powder removing device is already known in, for example, Japanese Patent Laid-Open No. 8-296089 (1996).
In this equipment, there is provided a metal powder removing portion for removing the metal powder contained in the treatment liquid, which comprises a cylindrical powder collector portion projecting into a circular passage in which the treatment liquid is circulated, and a powder collector magnet which is freely movable both inside and outside of the cylinder of the powder collector portion, and can thereby attract the metal powder from the treatment liquid bypassing within the circulating passage and attach or adhere it upon a surface of the powder collector portion. Further, when the powder collector portion is being cleaned, it is connected to a cleaning circuit by controlling valves provided therearound, and after the powder collector magnet is drawn out from inside of the cylinder of the powder collector portion so as to determine the effect of magnetic powder thereof, cleaning liquid and cleaning air are introduced to clean out and remove the metal powder attached to the surface of the powder collector portion, etc. This cleaning operation is conducted periodically.
However, with the prior art mentioned above, since the cleaning operation is done periodically, if the amount of the metal powder that is generated increases, for instance, due to changes in the production volume or changes in the type of production, a large amount of the metal powder accumulates upon the surface of the powder collector portion in layers and exceeds a practical limit. If the amount being collected exceeds the limit in this way, a portion of the metal powder in a cake or mass can be peeled off from the portion being accumulated in layers. Therefore, there are drawbacks in that the excess powder is turned back (leaked) into a processing container through the circulating passage, for example, and that it becomes disadvantageously attached onto the surface of the car body thus giving poor results, since it carries some amount of magnetism.